DIMM Issue... Asus Z77-V Pro (only showing 8 GB... 16 installed)

1600 MHz is usually an Overclock. Double check the timings and the voltage settings. If you're not sure you can reset the bios by pushing the reset cmos button or removing the cmos battery for a few seconds. Make sure you check the disk drives are in ide or ahci mode so you can set it back again before trying to start your operating system. If that gives you the 16 back you can try redoing the overclock. Otherwise you will need to download and run memtest86 available here - http://www.memtest86.com/download.html - get the one you need.

Agreed, could definitely be the OC causing the RAM to become unstable.

Also, are there any BIOS updates available for your board? Often BIOS updates cover RAM issues

Thanks for the quick replies.

The board is an Asus Z77-V Pro.

The oc was done in Bios.

I have installed all the drivers i could find but i cant recall a bios one.

I have tested all the ram individually on the board with the oc on and all worked at 1600. Could it be the slot + the oc causing instability?

Cheers

Check ASUS's website for a BIOS update, it would be under downloads, but it is not a driver.

Okay I updated the BIOS to 0906 successfully (turns out I missed that update when I setup...)...

I disable the OC before as well so it's showing 1333 and set to auto for RAM.

Still showing 8 GB Before Bios update and now after still also showing 8 GB....

Hrm...

Called Asus... did a CMOS battery reset...

Rebooted everything. Still only showing 8 GB. *perplexed*

Asus rep mentioned may have been a Windows update? I did download a couple updates last night that i didn't check over...

EDIT:

Actually I guess it cant be that cause the bios wont pick up the ram either...

the z77 chipset is very tuchy on the ram you use. if you look at asus ram guild there are sdome dimms that are fine for two slot...some for three and some for all four dimm slots. I would see if your ram is on the qual list.

It's very weird... it was working fine until this morning...

Totally baffled now.

I went back and tested every DIMM in every slot separately one at a time and all 4 sticks and all 4 slots are working fine.

For some reason with all in it's only showing 8 GB now.  

I changed the title for my thread as I can fairly safely say it's not a DIMM slot or DIM issue...

I thought I would bump to get advice on other aspects to check.

At the recommendations of another thread from a few months back (concerning checking RAM) I downloaded CPU-Z and had it pull up all my PC specs and perform a check, and sure enough it shows four DIMMs all running properly totally 16 GBs.

However both my BIOS and my OS only show 8 GB.  

Sticks check out, slots check out, board seems fine.

Bios is updated, chipset etc updated.

What else could this be?

Thanks for the help all.

EDIT:

Oh and oddly enough my Asus utilities tool also shows all 4 DIMMs running... but the BIOS doesn't.  

EDIT 2:

Also, as to the above, I don't see the RAM on the Asus recommended page but Corsair has this RAM listed as compatible with the board.

Update.

So I ran Memtest 86 and it also would only show 8 GB.

No errors.

So I ran each stick separate in their initial slot, 1 at a time.

No errors. All worked in each slot.

Here's some screens of the system info, Asus utility and CPUZ.







Very open on other things to check.

I ran dxdiag and it shows:

"Memory: 8192MB RAM"

but also,

"Page file: 2010MB used, 14281MB available"

support.microsoft.com/kb/2026022/en-us?p=1

helpdeskgeek.com/windows-7/fix-the-maximum-amount-of-memory-usable-by-windows-7-64-bit/

helpdeskgeek.com/windows-7/fix-the-maximum-amount-of-memory-usable-by-windows-7-64-bit/

ASUS doesn't always read 'SPD' information correctly so make the following (2) changes.
1. BIOS - AI Overclock Tuner -> XMP which should load Profile1 automatically e.g. DDR3-1600 9-9-9-24.
2. Page File - change both the minimum and maximum = 2048MB and reboot.

I assume if the problem persists that the Hardware Reserved >8192MB in the Resource Monitor. If the problem persists then add the following in the BIOS:
DRAM Voltage -> 1.55v
VCCIO Voltage -> 1.10v~1.15v

Thanks Unknown but I tried the Windows 7 64 bit system config setting already.

Hi Jaq. Bios OC is currently off. Was set to X.M.P. profile 1. showing as you have posted.

Haven't changed voltages.

Try the voltages, XMP works for (1) one set and (2) two sets is rolling the dice -- which is often fixed by slightly raising the voltages and/or manually setting the RAM manually:
DRAM Frequency -> DDR3-1600
CAS Timings -> 9-9-9-24
Command Rate -> 2 (2T, 2N or 2 same thing)
DRAM Voltage -> 1.55v
VCCIO Voltage -> 1.10v~1.15v

Failure then you have a bad stick or sticks...

Thanks jaq.

Well I ran it and it didn't fail but it still only shows the 8 GB with DRAM at 1.55v and VCCIO @ 1.12v.

Still stumped.

Minor update.

So I isolated down that the DIMMs are fine. I memo tested all again. All no errors.

I Installed in slots 1/2 and shows all 8.

I then installed in 3/4 and it shows only 4 GB.

I installed 1 in 3... shows 4 GB

Installed 1 in 4.... shows 4 GB?

This is where i'm running into issues isolating the problem.

What about 2/3 and 2/4?

Any combo with either 3 or 4 results in 8 gb showing... unless it's 3 and 4 then only 4 gb show.

After going over it with Asus they said it's likely a memory controller malfunction and to resturn the mb which im doing right now. Store testing it to make sure im not lieing.

Yup... NCIX tech couldnt figure out either. They tested the ram on a different board and it's fine and tried different ram on my board. 8 max no matter what. So yeay new board.

Best answer selected by LickTheEnvelope.

This topic has been closed by Nikorr